Electronics 3D Printing, Part Two: Direct Writing

As we already began to discuss in part one of this series, there are already a handful of companies that offer electronics 3D printing platforms and services. Perhaps the most notable, due to the fact that it offered the first commercial electronics 3D printing platform in 2003, is Optomec.

In 1999, Optomec, which had already begun commercializing directed energy deposition technology from Sandia National Laboratories, was awarded a $9 million contract from the Defense Advanced Research Projects Agency (DARPA) to develop a method for depositing a range of materials onto virtually any substrate, using a process known as “direct writing”.

This resulted in the Aerosol Jet Printing (AJP) process, which involves the atomization of a given material into a mist before that mist is focused and deposited using an inert gas, spraying it through a thin nozzle onto a substrate. AJP is capable of printing with a wide range of inks, including metals, resistor materials, nonmetallic conductors, dielectrics, adhesives, semiconductors, DNA and proteins. For final curing of many metal inks, 3D-printed objects must be heated in an oven.

Though the technology began directly printing functional antenna, battery, and passive components, as well as enzymes and living cells, in 2000, the first AJP system was released commercially in 2004. AJP has evolved from simple two-axis R&D systems to three- and five-axis machines, which Lite-On Mobile Mechanical SBG uses at its facility in Guangzhou, China to 3D print electronics onto millions of consumer electronics. The company sprays smartphone and tablet form-factors with electronic materials, running 24/7 production using the Aerosol Jet 5X five-axis machine.

While they may have become more of a name brand in the additive manufacturing space, Optomec wasn’t the only direct write company that was awarded a DARPA contract around the same time. In 1998, R&D firm Sciperio was awarded a DARPA grant to develop direct writing technology for printing electronics, including solar cells. This was followed on by numerous similar government-funded projects, as well as bioprinting initiatives.  In 2002, nScrypt was spun out of Sciperio to focus entirely on micro-dispensing and electronics 3D printing technology.

Today, nScrypt sells several direct write systems, including its Tabletop system and higher end  3Dn 300 and 500 systems, all of which rely on the company’s SmartPump dispenser. The SmartPump is capable of depositing over 10,000 commercially available materials, ranging from solder pastes and adhesives to living tissue. nScrypt has combined its various technologies to create hybrid manufacturing systems, capable of plastic extrusion, micro-milling, pick-and-place and other operations alongside dispensing of conductive inks and other materials with the SmartPump.

To perform Direct Digital Manufacturing (DDM) of electronics from CAD files, the nScrypt DDM “Factory in a Tool” platform combines “microdispensing, material extrusion, micro-milling, and pick and place tool heads with multiple cameras for automated inspection and computer vision routines, a point laser height sensor for mapping surfaces for conformal printing, an automated PulseForge 1300 photonic curing system, and a femtosecond laser for cutting or sintering materials, you can print a complex conformal antenna, followed by a circuit or electronic device with an embedded sensor, followed by a simple bracket, by simply changing the CAD file, with no human interaction with the tool.”

Though nScrypt’s platforms are more or less confined to smaller items, they are obviously quite versatile. The company recently discussed some of the applications for which its technology can be used, including bioprinting in space, in the video below.

More recently, a form of direct writing technology was commercialized by Voxel8, which took the pneumatic printhead developed in Jennifer Lewis’s lab at Harvard and integrated it into a desktop electronics 3D printer, dubbed the Developer’s Kit, capable of both printing plastic and depositing conductive inks. Unveiling the device at CES in 2015, the company wowed attendees with the ability to 3D print a complete, functioning quad copter that could fly right off the print bed.

Since then, it discontinued its Developer’s Kit and launched the Active Lab, which features a multi-input active mixing printhead to either spray or extrude liquid polyurethane elastomers onto a textile that then solidify as the elastomer reacts. The initial application for the technology is the fabrication of shoe uppers, with Voxel8’s technology able to provide structure to the otherwise two-dimensional and flimsy fabric, allowing it to become a three-dimensional cloth. The incorporation of an inkjet head makes it possible to provide digital coloration into the polyurethane and the fabric itself.

Others involved in direct write 3D printing are Neotech AMT—which combined AJP with its own five-axis print motion platforms to create printers capable of printing such 3D electronics as 3D Molded Interconnect Devices—and Integrated Deposition Solutions, Inc., which began licensing Sandia’s technology in 2013 to sell a desktop-sized printer, printing modules and printheads.

As these companies have demonstrated, direct write technology is one of the most versatile for printing electronics, but it is not the only method. In the next article in our series, we’ll take a look at inkjet and other photopolymerization technologies used in electronics 3D printing.